Hydroplane boat hull

ABSTRACT

The invention disclosed is an improved, hydroplane boat hull comprising a watertight interior skin, extending above the water line of the boat, an exterior skin having openings to the atmosphere for induction of air, and air ports beneath the water line for egress of air under pressure to lift the boat when the boat is propelled at a planing speed. The hull itself is formed with a pair of lower, elongated convex keels, each having a runner therealong, a forward, central boat keel having an air tunnel formed therein, and a central, generally rectangular air pressure duct extending along the terminus of the forward boat keel to the rear or transom of the hull, and being of decreasing cross-sectional area, from stem to stern, and communicating with the air exhaust ports in the exterior skin of the hull so that greater air pressure is maintained towards the transom of the boat than at the bow of the boat so as to lift the transom when the boat is at a planing speed. The transom may include a cavitation plate, and the hull itself is constructed of modular, precast units.

United States Patent [72] lnventor Milton A. Wallace 11 Colonial Ave., Cleveland, Ohio 441 10 [21] Appl. No. 817,688

[22] Filed Apr. 21, 1969 [45] Patented Feb. 9, 1971 [54] HYDROPLANE BOAT HULL 10 Claims, 13 Drawing Figs.

[52] US. Cl 114/67 [50] Field of Search 114/67.1, 67, 65.55

[56] References Cited UNITED STATES PATENTS 2,446,860 8/1948 Wallace 114/67 3,316,874 5/1967 Canazzi 114/66.5

3,382,833 5/ 1968 Wukowitz 1 14/665 Primary Examiner-Andrew H. Farrell Attorneys-Keith Misegades and George R. Douglas, Jr.

ABSTRACT: The invention disclosed is an improved, hydroplane boat hull comprising a watertight interior skin, extending above the water line of the boat, an exterior skin having openings to the atmosphere for induction of air, and air ports beneath the water line for egress of air under pressure to lift the boat when the boat is propelled at a planing speed. The hull itself is formed with a pair of lower, elongated convex keels, each having a runner therealong, a forward, central boat keel having an air tunnel formed therein, and a central, generally rectangular air pressure duct extending along the terminus of the forward boat keel to the rear or transom of the hull, and being of decreasing cross-sectional area, from stem to stem, and communicating with the air exhaust ports in the exterior skin of the hull so that greater air pressure is maintained towards the transom of the boat than at the bow of the boat so as to lift the transom when the boat is at a planing speed. The transom may include a cavitation plate, and the hull itself is constructed of modular, precast units.

- PATENTED FYEB 9 15m smurfs Baldwin-5151;151:515

INVENTOR I MILTON A. WALLACE j ATTORNEY PATENTEU FEB 9197i SHEET 2 BF 3 Q 31 FlG--.ll

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INVENTOR .MILTON A. WALLACE 2/ ATTORNEY PATENTED rm 9m: 3.561, 390

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INVENT OR MILTON A. WALLACE 7 41-1 D uii' ATTORNEY HYDROPLANE BOAT HULL BACKGROUND OF THE INVENTION The invention relates generally to boat hulls and more particularly to an improved, hydroplane boat hull adapted for use with pleasure boats rather than high'speed racing boats. The major problem of water displacement as the boat moves has been overcome by streamlining the boat hull so that the resistance of water displacement is reduced to a minimum. However, at least with pleasure craft, the problem of water drag resistance remains significant. Most often, the problem is met by constructing the boat hull so that positive trim is the result. In other words, the bow of the boat rides high in the water so that only a minimum portion of the stern remains in the water. Even so, fully one-half to two-thirds of the hull surface remain in the water, producing considerable resistance to forward movement by water drag.

The optimum solution to the problem is presented by modern hydroplane racing craft, commonly known as Three- Point Hydroplanes" wherein only a few square inches of dual sponson surface and one-half of a single propeller are in the water at full speed. However, such craft require power plants of tremendous size in relation tothe boat itself, and such construction has not been found feasible for common pleasure craft.

One solution to the problem is found in my earlier U.S. Pat. No. 2,446,860; the instant invention is intended as a substantial improvement thereover. The invention disclosed in my prior patent is a boat hull with a series of hydroplane steps having air passages therebetween and a plurality of ducts in the remainder of the hull and in the deck of the boat so as to reduce water drag. However, this invention still produced a boat with positive trim and entirely suitable handling characteristics.

Other attempts since the issuance of my patent include U.S. Pat. No. 3,I9I,572 issued to Henry A. Wilson and U.S. Pat. No. 3,316,874 issued to Henry D. Canazzi, both of which show air exhaust ports in the bottom surface of the hull for the purpose of reducing the water drag. U.S. Pat. No. 3,382,833 issued to Edward Wukowitz illustrates a double-hulled speedboat forming an air chamber from front to rear. U.S. Pat. No. 3,331,347 issued to Erik]. Von I-Ieidenstam illustrates a boat hull having a central air duct (FIGS. 18 and 19) communicating with hull passages to lift the boat hull out of the water, but this hull is designed for small craft only, and does not provide variable pressure beneath the hull so as to impart negative trim, rather than positive trim, to the boat at planing speed.

i The instant invention overcomes the disadvantages of the prior art by providing a hydroplane boat hull, suitable for use with trunk cabin-type cruisers, which imparts negative trim to the craft at planing speed, and yet additionally imparts excellent handling characteristics. Additionally, the hull of the instant invention may be constructed of modular precast units thereby substantially reducing the expense of constructing a pleasure craft, by entirely eliminating the need for a conventional boat keel and side ribs.

SUMMARY OF THE INVENTION The invention is an improved hydroplane hull which includes an interior, watertight skin and an exterior skinhaving air induction ports above the water level and air exhaust ports beneath the water line, the hull being constructed to form a pair of parallel, convex keels having runners therealong, a central boatstem having an air tunnel formed therein, and a central, generally rectangular air pressure duct, formed between the two convex keels, being constructed of decreasing cross-sectional area from stem to stem, and communicating with the air exhaust passages in the bottom of the hull so as to impart negativetrim to the boat when at planing speed. The keels are constructed of a plurality of similar, precast modular units which, when joined together, define the rectangular airp'ressure duct, which replaces the common keel, and each modular unit includes the vertical sidewall portion which includes a portion of the sidewall of the hull and thereby eliminates the need for conventional boat ribs. The deck of the boat may include additional air-inlet ducts communicating with the space defined by the inner and outer skins of the hull and the transom of the boat may be provided with a cavitation plate to assist in providing negative trim.

BRIEF DESCRIPTION OF THE DRAWING Details of construction according to preferred embodiments of the invention will become readily apparent by reference to the following drawing wherein:

FIG. 1 is a bottom, perspective view of the invention;

FIG. 2 is a side, elevational view of the invention as shown in FIG. I;

FIG. 3 is a bottom, plan view of the invention as shown in FIGS. 1 and 2;

FIG. 4 is a rear view of the transom of the invention;

FIG. 5 is a sectional view taken along lines 5-5 of FIG. 3;

FIGS. 6 and 7 are sectional views taken along lines 6-6 and 7-7 of FIG. 5, respectively;

FIG. 8 is an interior, perspective view of the invention, with parts broken away to show detail;

FIGS. 9 and 10 are sectional views taken along lines 9-9 and 10-10 of FIG. 1, respectively;

FIG. 11 is a partial, sectional view taken along lines 11-11 of FIG. 8;

FIG. 12 is a partial, sectional view taken along lines l2-I2 of FIG. 3; and

FIG. 13 is a perspective view of another embodiment of the invention, wherein the transom is modified to include a cavitation plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The boat 10 is shown comprising novel hull I2 and deck area 14. Hull 12 includes a bow stern portion 16 having a central bow keel 18 formed as an integral part thereof. The

remainder of the hull includes a pair of generally convex keels 20, 20, a central air pressure duct 22 and transom 24. The inner, watertight skin of the hull is formed by interior side walls 26 and decking 28 (FIGS. 8, I2) while the exterior skin includes the outer surface areas of bow keel I8, keel 20, and transom 24.

Primary air induction for hydroplane lift occurs through nose grate 30 of bow keel 18, at the stem of the boat through tunnel 32 of bow keel 18 to exhaust port 34 thereof. Secondary air induction for keels 20, 20 occurs through a plurality of slits or openings 36 formed in the exterior side skin 38 of hull I2, whereupon the air is fed downwardly between wall 26 and skin 38 to the water beneath keels 20, 20 (FIG. I2). These slits or openings 36 may be of various sizes and dimensions and may include a series of air ports 40 (FIG. 1 particularly towards the stern of the boat, in order to provide a maximum air supply for hydroplaning effect and negative trim at the stern of the craft.

As the figures indicate, each keel 20 comprises a plurality of alternate high steps 42 and low steps 44 which are spaced from each other to provide a plurality of air exhausts 46 between each step. Additionally, each keel 20 includes an elongated runner 48 which, in addition to imparting rigidity to the keel structure 20, provides a water biting" surface which imparts an unusual degree of stability to the craft when tuming either to port or starboard. The divergent shape of the center air pressure duct 22 is indicated by FIG. 3; as air moves towards transom 24 within duct 22, the reduced volume of duct 22 creates a greater pressure therewithin, and a consequent greater exhaust pressure through the rearmost exhausts 46 so that when the craft reaches a planing speed, the stern of the boat will be lifted above the water to impart negative, rather than common positive trim to the boat. On the other hand, the design of the boat keel 18 does impart positive trim to the bow 16 of the craft. Thus, when underway, both the stern and the bow of the boat are lifted up out of the water so that the craft rides level with respect to the surface of the water thereby providing a smoother ride for the occupants of the craft and, incidentally, imparting an additional safety feature to operation of the craft in that it will be easier to see ahead in a boat riding in negative trim.

The purpose of the alternate high step 42 and low step 44 is to eliminate even further the possibility of water drag when the boat is at a planing speed. The greater the speed of the craft, the higher it will ride in the water. At planing speed, only alternate low steps 44 will contact the water surface; the high steps 42 will be entirely out of contact with the water surface thereby reducing water drag almost 50 percent further. The obvious advantage of such construction is reduction in power requirements to maintain the boat at a planing speed.

For ease of construction, exterior skin 38 of hull 12 may be divided into sections 50 and 52 which may have their terminal, adjacent longitudinal edges curved inwardly (FIG. 9) and fastened together by suitable means such as bolts 54. A pair of curved, semiflexible members 56, 56 may be inserted between sections 50, 52 in order to form a side rubbing strake 58 for the craft. Referring to FIG. I0, deck 14 and upper section 50 may be joined together and covered by a longitudinally slit flexible tubing 60 to form a smooth sheer line.

A simple, inexpensive method of construction is provided by the instant invention which eliminates entirely the need for conventional hull ribs and a central keel. This construction is best indicated in FIG. 8. Rearwardly of the bow or stem 16, the remainder of the hull is constructed of a plurality of like, molded units which are individually cast and then joined together to form a complete hull. Each keel may be constructed of a plurality of molded units 62, each unit including a high step 42 and a low step 44. Of course, a wide variety of materials are available which are suitable for the instant invention. The most suitable material is probably cast resin with a fiberglass mat. The lip 64 of the complete molded units 62 provides a structural beam support while the rib 66 between steps 42 and 44 imparts additional strength. At the same time, interior side wall 26 may be constructed of a plurality of precast units 68 which may be ribbed at 71 in the form of a conventional rib. Similarly, exterior skin 38 may comprise a plurality of units 70, generally coextensive in size with each unit 68. Once cast, a section of the boat comprising molded unit 62 and units 68 and 70 may be joined together by suitable means, such as by bolts and/or epoxy resin compounds to form a hull section. A glance at FIG. 1 indicates that 16 of such units, 8 for each side of the craft may be prefabricated. The advantage of this type of construction is readily apparent. It permits an entire craft, on the order of the size of a cabin cruiser, to be prefabricated at a factory, with individual units packaged and shipped to a launch site where the units may be easily joined together to form the completed boat. The con sequent saving in labor and freight are significant. These completed sections may be joined together by suitable fastening means, such as epoxy resin, glues, bolts, etc., and the two sides of the boat will be joined together at the center by a plurality of flat steps 72, between internal adjacent edges of molded unit 62, 62.

, The chines 86, 86 are formed by additional lapped steps 88, 88, secured between the lateral, outer edges of units 62 and the bottom edges of units 70, forming exterior skin 38. Of course, additional hull lift is provided by air exhausting between adjacent steps 72 and 72, and between lapped steps 88 and 88.

The insertion of internal decking 28 completes the hull structure. As can be seen in FIG. 5, this construction provides a watertight interior hull formed by deck 28 and sidewall 26, and an exterior, previous hull, formed by skin 38, molded units 62, and fiat steps 72. At the same time, a "keel is defined by that portion of deck 28 between units 62, the interior facing edges of adjacent molded units 62, and the fiat steps 72. If additional lateral rigidity is deemed necessary, open channels may be inserted laterally of the boat, between adjacent pairs of molded units 62, and bolted or otherwise firmly secured thereto (not shown).

An alternate form of construction of transom 24, particularly suitable for use with outboard motors, is shown in FIG. I3. A central, cavitation plate 74, attached to car 76 and pivotally mounted therein at 78 may be adjusted to the desired angular deviation from the horizontal by use of pins (not shown) through bores 80, 80 formed in ear 76 and plate 74. Center pressure duct 22 terminates in an exhaust 82 in the vicinity of the cavitation plate 74, and a drain hole 84, for the internal cabin area may be provided. Similarly, the first embodiment of the invention described above will include such an exhaust 82 for duct 22 (FIG. 4).

The intended scope of the invention is considerably broader than the precise embodiments hereinbefore discussed which is apparent by reference to the following claims.

Iclaim:

1. In a boat hull comprising a watertight interior skin, extending above the waterline, and an exterior skin, having means defining openings to the atmosphere for induction of air between the skins and additional means defining openings in the exterior skin below the waterline for the egress of air, an improved boat hull construction comprising:

a. a pair of generally longitudinal convex keels, one on each side of the centerline of the boat, each running generally the substantial length of the boat;

b. a hollow boat keel extending generally from the stem of the boat, along its keel centerline to a point beyond the forward terminal ends of the pair of convex keels, centrally therebetween, and including:

1. means defining an air induction opening at the stem of the boat; and

2. means defining an air egress at the terminus of the bow keel, beneath the waterline; and

c. means defining a 'generally rectangular air pressure duct, formed along the lower centerline of the boat, above and between the convex keels, extending from, and fed by, the bow keel air egress to the stern of the boat hull, constructed in generally decreasing cross-sectional area from the stem to the stern of the boat and communicating with said exterior skin openings beneath the waterline whereby air under greater pressure is forced from the stern area of the boat than in the bow area to lift the stem and reduce water drag when the boat is at a planing speed.

2. The invention as recited in claim I wherein each of said convex keels includes a keel runner, extending generally the length of said convex keel, and mounted at the outermost, lower dependent portion thereof.

3. The invention as recited in claim I wherein each convex keel comprises a plurality of molded units, each unit comprismg:

a. a pair of molded steps extending outwardly and downwardly from the centerline of the hull towards the base of the convex keel, said steps defining an air egress therebetween and between adjacent sets of steps; and

b. means defining a concave opening in the outermost dependent portion of each step, running generally parallel to the centerline of the boat.

4. The invention as recited in claim 3 wherein each said pair of molded steps includes a forward, high step, and a rear, low step, said low step only being in contact with the water when the boat is at a planing speed.

5. The invention as recited in claim 3 wherein the transom of said boat includes acavitation plate, selectively adjustable to differing angular positions with respect to a horizontal plane, to assist the air pressure duct in lifling the stern of said boat when at a planing speed.

6. The invention as recited in claim 3 wherein said rectangular air pressure duct isdefined by a portion of the inner hull skin located above and between the convex keels, the inner. terminal, facing edges of the plurality of molded units defining the two convex keels, and a plurality of steps mounted between the lower portions of the said inner terminal facing edges of the plurality of molded units.

7. The invention as recited in claim 6 wherein said plurality of steps comprise one of each facing, adjacent pair of molded units, said steps arranged in overlapping, shingle fashion so as to form an air egress, between adjacent steps, directed away from the path of travel of the boat.

8. The invention as recited in claim 3'wherein each molded unit of the convex keels includes a vertical, side wall portion which comprises a portion of the inner skin of the hull, being of a length substantially equal to the width of one of the molded units, said vertical side wall portion including suitable rib structure to maintain the integrity of the completed hull,

whereby the entire hull, rearwardly of the stern of the boat, is constructed of a plurality of said molded units without a conventional boat keel or side ribs.

- 9. The invention as recited in claim 8 wherein adjacent molded units are joined together by a portion of the inner hull skin and portions of the exterior skin of the hull.

10. The invention as recited in claim 3 wherein said boat hull includes a deck having means defining a plurality of air inlets therein, communicating with the space defined by the inner and exterior skins of the hull. 

1. In a boat hull comprising a watertight interior skin, extending above the waterline, and an exterior skin, having means defining openings to the atmosphere for induction of air between the skins and additional means defining openings in the exterior skin below the waterline for the egress of air, an improved boat hull construction comprising: a. a pair of generally longitudinal convex keels, one on each side of the centerline of the boat, each running generally the substantial length of the boat; b. a hollow boat keel extending generally from the stem of the boat, along its keel centerline to a point beyond the forward terminal ends of the pair of convex keels, centrally therebetween, and including:
 1. means defining an air induction opening at the stem of the boat; and
 2. means defining an air egress at the terminus of the bow keel, beneath the waterline; and c. means defining a generally rectangular air pressure duct, formed along the lower centerline of the boat, above and between the convex keels, extending from, and fed by, the bow keel air egress to the stern of the boat hull, constructed in generally decreasing cross-sectional area from the stem to the stern of the boat and communicating with said exterior skin openiNgs beneath the waterline whereby air under greater pressure is forced from the stern area of the boat than in the bow area to lift the stern and reduce water drag when the boat is at a planing speed.
 2. means defining an air egress at the terminus of the bow keel, beneath the waterline; and c. means defining a generally rectangular air pressure duct, formed along the lower centerline of the boat, above and between the convex keels, extending from, and fed by, the bow keel air egress to the stern of the boat hull, constructed in generally decreasing cross-sectional area from the stem to the stern of the boat and communicating with said exterior skin openiNgs beneath the waterline whereby air under greater pressure is forced from the stern area of the boat than in the bow area to lift the stern and reduce water drag when the boat is at a planing speed.
 2. The invention as recited in claim 1 wherein each of said convex keels includes a keel runner, extending generally the length of said convex keel, and mounted at the outermost, lower dependent portion thereof.
 3. The invention as recited in claim 1 wherein each convex keel comprises a plurality of molded units, each unit comprising: a. a pair of molded steps extending outwardly and downwardly from the centerline of the hull towards the base of the convex keel, said steps defining an air egress therebetween and between adjacent sets of steps; and b. means defining a concave opening in the outermost dependent portion of each step, running generally parallel to the centerline of the boat.
 4. The invention as recited in claim 3 wherein each said pair of molded steps includes a forward, high step, and a rear, low step, said low step only being in contact with the water when the boat is at a planing speed.
 5. The invention as recited in claim 3 wherein the transom of said boat includes a cavitation plate, selectively adjustable to differing angular positions with respect to a horizontal plane, to assist the air pressure duct in lifting the stern of said boat when at a planing speed.
 6. The invention as recited in claim 3 wherein said rectangular air pressure duct is defined by a portion of the inner hull skin located above and between the convex keels, the inner, terminal, facing edges of the plurality of molded units defining the two convex keels, and a plurality of steps mounted between the lower portions of the said inner terminal facing edges of the plurality of molded units.
 7. The invention as recited in claim 6 wherein said plurality of steps comprise one of each facing, adjacent pair of molded units, said steps arranged in overlapping, shingle fashion so as to form an air egress, between adjacent steps, directed away from the path of travel of the boat.
 8. The invention as recited in claim 3 wherein each molded unit of the convex keels includes a vertical, side wall portion which comprises a portion of the inner skin of the hull, being of a length substantially equal to the width of one of the molded units, said vertical side wall portion including suitable rib structure to maintain the integrity of the completed hull, whereby the entire hull, rearwardly of the stern of the boat, is constructed of a plurality of said molded units without a conventional boat keel or side ribs.
 9. The invention as recited in claim 8 wherein adjacent molded units are joined together by a portion of the inner hull skin and portions of the exterior skin of the hull.
 10. The invention as recited in claim 3 wherein said boat hull includes a deck having means defining a plurality of air inlets therein, communicating with the space defined by the inner and exterior skins of the hull. 